The invention relates to a strain relief element for a cable having one or more conductors, and a respective plug with said strain relief element.
Each conductor in the cable is covered by an insulating, and a cable sheathing is surrounding and fixing the one more insulated conductors. In case of one single insulated conductor, the cable sheathing and the insulating of the conductor can be formed by one integral part surrounding the conductor or by an additional cover different from the insulating of the conductor. In case of a plurality of different insulated conductors, the cable sheathing is preferably an additional cover surrounding all inductors, e.g. as a plastic coating manufactured around the insulated conductors or as a tape, such as a fabric tape, wrapping the insulated conductors. The cable sheathing is thus a means for surrounding the plurality of insulated conductors and fixing them close to each other to form a cable.
The cable further has a corrugated tube surrounding the cable sheathing along its longitudinal direction at least partially. Partially surrounding means that the corrugated tube is surrounding the cable sheathing in such way that at least one end or section of the cable sheathing is protruding from the corrugated tube. This at least one end or section of the cable sheathing protruding the corrugated tube might in particular be a connection part of the cable that might be housed in a plug, socket or the like connection means. The part of the cable with the cable sheathing protruding the corrugated tube is usually at an end of the cable. However, this part of the cable might also be an intermediate section of the cable without the corrugated tube.
A strain relief element is attached to the cable and hold in the plug, socket or the like connection means. It is fixing the cable, or at least the conductor or conductors relative to the housing of the plug, socket or the like connection means against a tractive force executed on the cable relative to the plug, socket or the like connection means. The aim of such strain relief elements is to protect the electrical connection of the conductor or conductors to the plug, socket or the like connection means, and in particular to a contact insert thereof, against damage form such tractive force. Such strain relief elements are commonly known and used.
Such strain relief elements are often integrated into the plug, socket or the like connection means as an integral part. It is known form DE 10 2005 030 554 A1 to integrate such strain relief elements into the cable opening of the plug composed of two half-body elements or shells. When the two half-body elements are assembled, the strain relief element is formed clamming the cable sheathing with a clamping force. The clamming force might be reinforced by an additional clamping element, such as a cable tie. However, the handling is quite complicated as the strain relief element must be fixed or attached at the cable when the housing of the plug is assembled.
The proposed strain relief element has a clamping collar means in form of an at least partially closing ring for clamping said cable sheathing arranged in a clamping opening of the ring. The clamping takes place in particular at a part of the cable sheathing protruding the corrugated tube. The clamping collar means provides a first and a second half-ring clamping element with a partial clamping opening each and hinged together through a first hinge. The clamping opening is defined by folding the two half-ring clamping elements towards each other around the first hinge. In this case, the partial clamping openings of the two half-ring elements form a ring around the cable sheathing. The clamping opening is fixed around the cable sheathing with a clamping force executed by a clamping element. The ring defined by the clamping collar means might be completely closed. However, according to an advantageous embodiment, the ring comprises a gap. This means that the ring is surrounding the cable sheathing apart from this remaining gap. This gap is preferably significantly smaller than the outer diameter of the cable sheathing with the effect that the cable is secured inside the ring and cannot be pulled through the gap. This is described by the fixing collar means forming a partially closing ring.
In the WO 2007/113307 A1 a cable connector assembly for a cable is described that having a similar strain relief element with first and second separate shells. Both shells connected together to form the housing of the connector assembly. The cable is positioned between the two shells before assembling the housing. In the part of the cable surrounded by the two shells, a strain relief means is tightly surrounding a segment of the insulating sheath of the cable. The strain relief means comprises at least first and second portions hinged together. When folded towards each other, the first and second portions surround the cable entirely and are fixed by a snap fit connection. It is a disadvantage of this cable connector assembly that a protecting corrugated tube surrounding the cable sheathing cannot be attached the connector assembly. Thus, during use, the corrugated tube might misalign on the cable sheathing relative to the connector assembly with the effect that the cable sheathing is not protected by the corrugated tube and thus exposed to a possible damage.
The DE 20 2009 015 571 U1 discloses a an electrical plug with a separate adapter part with an outer surface adapted to an inner surface of the plug housing and with an inner surface structure adapted to be attached to the sheathing of the cable, the sheathing being in form of a corrugated tube. The adapter part has two half-shells hinged to an adapter part body. The major drawback of this disclosure is that the conductors contained in the corrugated tube are not secured or clamped. Accordingly, this solution can only be used to attach the corrugated tube to the plug but not as strain relief element. It is not possible to execute a high clamping force to the corrugated tube without damaging the corrugated tube and/or the conductors guided in the corrugated tube.
Same applies for a similar adapter for fixing a corrugated tube disclosed in US 2004/0187258 A1 having a main body and a lid coupled via a bendable hinge to hold a corrugated tube surrounding a cable. A strain-relief of a cable guided in the corrugated tube is not possible.
It is accordingly an object of the present invention to provide a strain relief element that enables to fix a corrugated tube surrounding the cable sheathing of the cable and that is to handle for both, fixing the corrugated tube and attaching the strain-relief element to the cable.
This object is achieved with a strain relief element according to claim 1 and a plug with that strain relief element according to claim 13.